When plants are grown in a flat bed under a lamp, the plants are at varying distances from the lamp. Greater efficiency in the use of the light is obtained where all the plants being illuminated by a given light source are equidistant from it, reducing the number of lights needed for each productive square unit of growing area. This can be achieved by means of a rotary growing apparatus in which the plants are rotated about a light source at the axis of rotation.
U.S. Pat. No. 6,604,321 (Marchildon) discloses a rotary plant-growing apparatus with an open-ended cylindrical drum which rotates about a horizontal axis on a support stand. A lamp is positioned at the axis of the drum. Holes in the drum hold plant pots, with the plants facing the light and the bottom of the pots extending radially outward from the drum. A tray under the drum holds a pool of water and is spaced from the drum such that the lower part of the pots contacts the water as the drum rotates, watering the plants.
Canadian published patent application 2,401,737 (Poirier et al.) discloses a rotary growing apparatus which comprises a cylindrical structure or drum provided with a series of parallel elongated, longitudinally extending baskets for holding plants. A support base is provided for the drum, and a drive mechanism rotates the drum on the support base about the drum's rotational axis. A light source is positioned inside the drum. A feeding system provides nutrient fluid to the growing plants as the drum rotates and the baskets contact the nutrient fluid. The elongated baskets define in the bottom and side walls thereof a plurality of apertures for allowing the nutrient fluid to access the plants. The elongated baskets are removably attached to a pair of parallel and opposed rims of the drum by means of tubular members with resilient attachment pins at the ends thereof.
Although rotary growing machines of the foregoing types reduce the amount of floor space required for growing a given number of plants, as compared to traditional methods of using flat beds or trays of plants, much more efficient use of floor area could be achieved by providing for movement of rotary plant-growing modules from one point to another while the machines continue to operate. For example, if the plant-growing machines can be moved vertically, a plurality of such machines could be operated in less floor space than they would occupy if placed on a floor. Also, in some situations, floor space could be saved by providing for horizontal movement of a plurality of plant-growing machines, for example moving them between areas where there is insufficient space for servicing them and an area where they can be serviced. It would be desirable to provide a plant-growing apparatus for effecting movement of a plurality of such machines from one point to another while the machines continue to operate.